In many use cases strain gauges are used for sensing a load. However, strain gauges often require a structural weakening of the load conducting elements. Often, there is a need for load measurements without compromising on structural stability.
This is especially true for tow couplings. Furthermore, there is a strong demand for smart tow couplings, e.g. for systems providing a load weight gauge (measuring the tongue load of a tow coupling), a tow load weight shift alert, an unsafe trailer load distribution alert, a vehicle limit notification, an automated trailer brake control (closed loop), a low/flat trailer tire notification, and a check trailer brake notification, closed loop braking control, vehicle shift control, engine control, and stability control. The above discussed functions require the measurement of tow loads and/or tongue loads of the tow coupling.
Prior art load measurement devices for tow couplings have significant shortcomings, e.g. the complexity of the measurement and control devices, and the costs of the sensor assembly.
As an alternative to the widely used strain-gauges, non-contact type sensors exploiting the magnetoelastic effect were developed. These are frequently applied for torque measurements at rotating shafts in various mechanic systems. U.S. Pat. No. 9,347,845 discloses such a magnetoelastic sensor. U.S. Pat. No. 9,347,845 is incorporated herein by reference in its entirety.